Adding a sub child to boost ptree - c++

Question

Lets say I am aiming to create an xml in the following form:
<main>
<elements>
<element name="elem1"><temp/>
</element>
<element name="elem2"><temp/>
</element>
</elements>
</main>
I have the following code:
ptree pt;
pt.put("main","");
ptree temp1;
temp1.put("element","");
temp1.put("element.<xmlattr>.name","elem1");
temp1.put("element.temp");
ptree temp2;
temp2.put("element","");
temp2.put("element.<xmlattr>.name","elem2");
temp2.put("element.temp");
//temp1 represents the 1st <element>...</element>
//temp2 represents the 1st <element>...</element>
//Add temp1 and temp2 to <main> under <elements>
I would assume the following would work:
pt.add_child("main.elements",temp1);
pt.add_child("main.elements",temp2);
However this generates the following xml:
<main>
<elements>
<element name="elem1"><temp/>
</element>
</elements>
<elements>
<element name="elem2"><temp/>
</element>
<elements>
</main>
I was able to get the required xml file by making my temp1 in the following form:
temp1.put("<xmlattr>.name","elem1");
temp1.put("temp","");
temp2.put("<xmlattr>.name","elem2");
temp2.put("temp","");
pt.add_child("main.elements.element",temp1);
pt.add_child("main.elements.element",temp2);
Is there a way I can work with my initial temp1 and temp2 nodes to get the desired xml structure?

Answer 1

Your situation is a bit suboptimal (and I'd very much favour the working snippet you gave).
Here's what would work:
pt.add_child("main.elements.element", temp1.get_child("element"));
pt.add_child("main.elements.element", temp2.get_child("element"));
Live On Coliru
#include <boost/property_tree/xml_parser.hpp>
#include <iostream>
using boost::property_tree::ptree;
int main() {
ptree temp1;
temp1.put("element.<xmlattr>.name","elem1");
temp1.put_child("element.temp", {});
ptree temp2;
temp2.put("element.<xmlattr>.name","elem2");
temp2.put("element.temp", "");
//Add temp1 and temp2 to <main> under <elements>
ptree pt;
pt.add_child("main.elements.element", temp1.get_child("element"));
pt.add_child("main.elements.element", temp2.get_child("element"));
write_xml(std::cout, pt, boost::property_tree::xml_writer_make_settings<std::string>(' ', 4, "utf-8"));
}
Prints
<?xml version="1.0" encoding="utf-8"?>
<main>
<elements>
<element name="elem1">
<temp/>
</element>
<element name="elem2">
<temp/>
</element>
</elements>
</main>